Network Solution for Windows – Windows system, Linux system, Ubuntu server configuration tip

Network Address Translation is a technical amendment to allow the address of Header packets when moving through the device with Routing features, the goal to map the network address to the other party ….

NAT service in the Windows Server version allows you to connect the private network, IP address locally the Internet. NAT server will block the request by the Internet client, change the value on the address to send packets to IP addresses outside your network card NAT Server and send out the Internet. When data received answers from the Internet, NAT Server will check the “NAT table” and its right to the computer that requested the local LAN.

Indeed, the Windows Server NAT is an adapter address and port, because the NAT does not only convert the IP address where to send data packets over IP, but it also convert the port to send data .

1. Support the Advanced NAT

NAT not only allows you to connect separate networks but Internet allows you to go from the Internet to your own network. When this, you are making a “reverse NAT” – “NAT contrary.” The IP address of the Internet outside the host will be replaced by the address card Internet NAT server, forwarded to the host in a local area network with the source address is the address of the card Internet NAT server.

You can also configure the NAT server supports the need to use the port defined on it before. Many games require online game game server on the Internet can send answers to your computer in a port or a port range is specified.

2. Card Address Pool

After configuration Internal and External card will be used by the NAT server, you must click on the card and select Properties External. In the Properties dialog box appears, select the Address Pool tab.

Effects of Pool Address card is what? If you have multiple IP address lease from the ISP, you can configure the NAT server to use all of them for the address change. Click on Add button, enter the starting address, subnet-mask and end address. You note that the program will automatically calculate the final address in the network corresponding to the start address and subnet-mask that you entered. If necessary, you can change, but if you can not leave the same.

Then, NAT server will use all the address you have added to the Address Pool tab to switch addresses. For example I added the public IP address as follows:

1. 192.168.1.1
2. 192.168.1.2
3. 192.168.1.3

And computers in the Internal network will be assigned the address on accessing the Internet. Suppose client 01 when accessing the Internet will use the address 192.168.1.1, client 02 using the address 192.168.1.2, client 03 using the address 192.168.1.3. If client access to the Internet, client and two 01 and 02 have not expired use public address, the next client will use the address 192.168.1.3.

3. Reserve public address

You can do vice versa, ie using a public IP address in the Address Pool list and then just for a computer network is Internal. For example, in a network you have an Internal 172.16.0.10, and you want that machine to use the public IP address is 192.168.1.3. When the machine in Internal 172.16.0.10 will always be “priorities” to use public address 192.168.1.3, not a computer in any other used Internal address 192.168.1.3 in the NAT. If you want to transfer all connected to the public address 192.168.1.3 to the computer of the Internal 172.16.0.10 CheckBox to “Allow incoming sessions to this address”.

To open the Add Reservation dialog box, you click the Reservations button on the Properties dialog of the network card.

Our example the application of useful features. You have an email server o the Internal network, the address 172.16.0.10, you can configure NAT Reservation all transfer request to the address 192.168.1.3 to the public in Internal email server. It also avoid the other client machines in Internal use public IP address 192.168.1.3.

4. The NAT gateway special:

Many times you want to control the packets will be sent to servers in the Internal. In the example above, all packets sent to the address 192.168.1.3 will go to the email server computer in Internal. You may not want to completely like you want the packets on port 25 is delivered to the email server. You do not want packets in the port are sent to the email server.

In this case, instead of creating an Reservation, you can add a “special ports. Card Services and to the Port, you can select a service available in the list if you want to configure in it. Windows Server 2003 automatically generates a lot for the service port to use. If not you can click Add to create a new service on the port you want.

In the Description of Service, you enter the description for the service. At the public address, you can select “Address pool entry” and enter the public IP address you want to use. You fill in protocol, private address – the address of the host in the corresponding internal, Incoming and Outgoing Port Port. Note that before creating a service, you must create the address in Address Pools and External network card you should use static IP addresses.

Many people do not understand Incoming and Outgoing Port Port is nothing. Incoming Port is a port for requests from the Internet, and is Outgoing Port NAT server you want to use when it sends request to host the Internal network card from Internal. Often the Incoming and Outgoing Port Port identical, for example an SMTP Server is 25.

5. Summarized

NAT is a great service. It allows client from using the Internal IP address local to connect to the Internet and vice versa, you can configure to forward packets to an external address to an address is local. It is a technical “reverse NAT”, which allows Internet users access to resources in a local area network. You can configure forwarding all traffic to an address in the internal, or only allow packets on the port defined through the media using the Services and Ports.